Earlier this month, Facebook launched a significant update to its Page Manager app. One of the things within the app was the ability for businesses to manage their pages — for brands, this is incredibly important because whether they’re at an event, conference, trade show or wherever, it’s helpful to have mobile access to update your company’s Facebook page.

Additionally, it now lets businesses buy promoted postsdirectly from the mobile device — something that has never been available until now. Oh, and here’s the thing, the new mobile advertising interface was all done up by an intern.

In a post shared on Facebook’s engineering blog, Peter Cottle reminisced about his experience playing a role in implementing the first ever mobile advertising interface for the social network. In it, he describes how he mistakenly thought that to have an impact on assigned projects, he would be writing unit tests or writing documentation. Soon he discovered it was much more extreme than that.

Cottle says that his project was the evolution of several events taking place within Facebook concurrently: promoted posts for the desktop, the company’s shift towards mobile, and the release of page manager for iOS. From there, he became responsible for merging the three together into something that would work, which he readily admits wasn’t a small challenge.

Throughout the experience, he wasn’t left alone to squirm under pressure. Cottle writes about receiving mentorship, collaboration, advice, and feedback from anyone he asked within the company, helping him learn and succeed at each turn.

A feature widely requested from small businesses, Facebook has seen some success of Cottle’s work already. In one example, the barbeque sauce Bone Suckin’ Sauce promoted a variety of its Page posts and created marketplace ads that targeted Likes and interests relating to “backpacking”, “feef jerky”, “camping”, and “fishing”, along with friends already connected to the Page. It quickly saw an 83% increase in online store sales directly attributed to promoted posts.

Meredith Manor, an equestrian career college/vocational school, set up promoted posts to help achieve its goal of increasing awareness about its existence. Promoted posts included a photo post of an advanced student taking her horse over a challenging jump to illustrate a student’s succes. Marketplace ads and targeted Likes and interests were also used. The result was four times more people reached out through promoted posts than non-promoted posts. Over three times more users engaged and led to a 30% increase of prospective students signing up.

So what does Cottle think about his work and the difference he’s made to Facebook’s community?

It felt great to put so much effort into a historic interface and see our work make the ship deadline. I’m really proud of the feature, thankful for the opportunity, and excited to demonstrate Facebook’s dedication towards mobile. Even better, I’ll get to experience Facebook’s culture full time when I return in the Spring.